001    package org.apache.myfaces.tobago.util;
002    
003    /*
004     * Licensed to the Apache Software Foundation (ASF) under one or more
005     * contributor license agreements.  See the NOTICE file distributed with
006     * this work for additional information regarding copyright ownership.
007     * The ASF licenses this file to You under the Apache License, Version 2.0
008     * (the "License"); you may not use this file except in compliance with
009     * the License.  You may obtain a copy of the License at
010     *
011     *      http://www.apache.org/licenses/LICENSE-2.0
012     *
013     * Unless required by applicable law or agreed to in writing, software
014     * distributed under the License is distributed on an "AS IS" BASIS,
015     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016     * See the License for the specific language governing permissions and
017     * limitations under the License.
018     */
019    
020    import org.apache.myfaces.tobago.context.ClientProperties;
021    
022    import javax.faces.application.Application;
023    import javax.faces.context.FacesContext;
024    import javax.faces.el.ValueBinding;
025    import javax.faces.el.VariableResolver;
026    
027    public final class VariableResolverUtils {
028    
029      private VariableResolverUtils() {
030        // utils class
031      }
032    
033      /**
034       * Returns the requested object configured in the faces-config or from library.
035       */
036      public static Object resolveVariable(FacesContext context, String variable) {
037    // TODO: JSF 1.2
038    //    if (FacesVersion.supports12()) {
039    //      final ELContext elContext = context.getELContext();
040    //      return elContext.getELResolver().getValue(elContext, null, variable);
041    //    } else {
042          final Application application = context.getApplication();
043          final VariableResolver variableResolver = application.getVariableResolver();
044          return variableResolver.resolveVariable(context, variable);
045    //    }
046      }
047    
048      /**
049       * Returns the ClientProperties object configured in the faces-config.
050       */
051      public static ClientProperties resolveClientProperties(FacesContext facesContext) {
052        return (ClientProperties) resolveVariable(facesContext, ClientProperties.MANAGED_BEAN_NAME);
053      }
054      
055      /**
056       * Clears the value of the variable.
057       * Useful for cleaning up e.g. a session or application variable
058       * to save memory without the knowledge of the scope.
059       * Also useful to enforce a new creation of a managed-bean.
060       */
061      public static void clearVariable(FacesContext context, String variable) {
062    // TODO: JSF 1.2
063    //    if (FacesVersion.supports12()) {
064    //      final ELContext elContext = context.getELContext();
065    //      elContext.getELResolver().setValue(elContext, null, variable, null);
066    //    } else {
067          final Application application = context.getApplication();
068          final ValueBinding valueBinding = application.createValueBinding("#{" + variable + "}");
069          valueBinding.setValue(context, null);
070    //    }
071      }
072    }